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Incorporation of methyl lysine into polypeptides

a technology of methyl lysine and polypeptides, which is applied in the field of genetically encoding nemethylllysine in recombinant polypeptides, can solve the problems of unpredictable effects on the properties of analogs, difficult comparisons between analogs and natural modifications, and often challenging experiments

Inactive Publication Date: 2014-09-25
MEDICAL RESEARCH COUNCIL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0036]Conditions and / or times for removal may easily be optimised by the skilled worker. Suitably the conditions and / or times used are chosen to maximise removal of the R- group whilst minimising any other chemical changes which might be catalysed by the treatment. The effects of the treatment may be easily monitored using (for example) mass spectrometry (MS) techniques as described in the examples section.Orthogonal tRNA Synthetase-Orthogonal tRNA Pairs
[0063]Unnatural amino acid incorporation in in vitro translation reactions can be increased by using S30 extracts containing a thermally inactivated mutant of RF-1. Temperature sensitive mutants of RF-1 allow transient increases in global amber suppression in vivo. Increases in tRNACUA gene copy number and a transition from minimal to rich media may also provide improvement in the yield of proteins incorporating an unnatural amino acid in E. coli. Industrial Application

Problems solved by technology

Researchers have used methyltransferases to methylate histones5, but in many cases this is unsatisfactory because it is difficult to control the site, extent or degree of methylation using these enzymes in vitro.
These experiments are often challenging and require synthesis of large quantities of peptide thioesters.
Taken together these differences may lead to unpredictable effects on the properties of the analogs.
Since these analogs are created for the purpose of discovering unknown properties of the natural system, or explaining known phenomena in molecular detail, differences between the analogs and the natural modification are problematic.

Method used

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  • Incorporation of methyl lysine into polypeptides
  • Incorporation of methyl lysine into polypeptides
  • Incorporation of methyl lysine into polypeptides

Examples

Experimental program
Comparison scheme
Effect test

example 1

Production of Polypeptide Comprising Nε-Methyl-Lysine

[0109]We realized that we might be able to encode Nε-methyl-L-lysine (3) indirectly by providing the synthetase enzyme with a substrate that was significantly different from both Nε-methyl-L-lysine and L-lysine if we were able to subsequently effect the facile, quantitative and specific post-translational conversion of this precursor to Nε-methyl-L-lysine on the synthesized protein. Since Nε-tert-butyl-oxycarbonyl-L-lysine (1) is an efficient substrate for the pyrrolysyl-tRNA synthetase / tRNACUA pair19 we asked whether Nε-methyl-L-lysine (3) could be incorporated into proteins in a two-step process in which Nε-tert-butyl-oxycarbonyl-Nε-methyl-L-lysine (2) is genetically incorporated into proteins and the tert-butyl-oxycarbonyl group is removed post-translationally to reveal Nε-methyl-L-lysine (see FIG. 1—Strategies for encoding lysine methylation. A. amino acids used B. Schemes for encoding 3 in recombinant proteins.)

[0110]To inves...

example 2

MS Analysis

[0111]To demonstrate that 2 can be incorporated with high fidelity into recombinant proteins and is not subjected to in vivo modification14, we performed electrospray ionization mass spectrometry (ESI-MS) on the purified protein. The ESI-MS spectra of myoglobin-His6 demonstrates the quantitative incorporation of 2 (FIG. 7A). These data demonstrate that 2 can be genetically encoded in proteins in good yield and with high fidelity using MbPylRS / MbtRNACUA pair.

example 3

Application to Histones

[0112]To specifically and efficiently introduce 2 in a histone at physiologically relevant site, we transformed E. coli BL21(DE3) with pBKPylS and pCDF-PylT-H3K9TAG (a vector which encodes MbtRNACUA and a N-terminally hexahistidine tagged histone H3 gene in which the codon for lysine 9 is replaced with an amber codon)15. We grew the cells in the presence of 2 mM 2, and expressed and purified the recombinant histone in good yield (2 mg per liter of culture). ESI-MS analysis of the purified histone confirms the incorporation of 2 into histone H3 (FIG. 7B).

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Abstract

The invention relates to A method of making a polypeptide comprising at least one Nε-methyl-lysine at a specific site in said polypeptide, said method comprising (a) genetically directing the incorporation of R—Nε-methyl-lysine into said polypeptide, wherein R comprises an auxiliary group; and (b) catalysing the removal of R from the polypeptide of (a). In particular the invention relates to such a method wherein genetically directing the incorporation of R—Nε-methyl-lysine into said polypeptide comprises arranging for the translation of a RNA encoding said polypeptide, wherein said RNA comprises an amber codon, and wherein said translation is carried out in the presence of an amber tRNA charged with R—Nε-methyl-lysine.

Description

[0001]The present application is a continuation of U.S. patent application Ser. No. 13 / 499,450, which was filed Jun. 12, 2012, which was filed pursuant to 35 U.S.C. 371 as a U.S. National Phase application of International Patent Application No. PCT / GB2010 / 001847, which was filed Oct. 1, 2010, claiming the benefit of priority to British Patent Application No. 0917240.4, which was filed on Oct. 1, 2009. The entire text of the aforementioned applications is incorporated herein by reference in its entirety.FIELD OF THE INVENTION[0002]The invention relates to genetically encoding Ne-methyl-L-lysine in recombinant polypeptides.BACKGROUND TO THE INVENTION[0003]The Nε-methylation status of specific lysine residues on histone proteins in chromatin controls heterochromatin formation, X-chromosome inactivation, genome imprinting, DNA repair, regulates transcription and may define epigenetic status1-3. The reversible post-translational methylation of lysine residues in histones is mediated by ...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C07K14/47G01N33/566
CPCG01N33/566C07K14/47C12N9/93C12P21/02
Inventor CHIN, JASONNGUYEN, DUY P.
Owner MEDICAL RESEARCH COUNCIL
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